Fair Value Measurements - Changes in balances of Level 3 financial liabilities carried at fair value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, Beginning Balance	$ (2,542)	[1]	$ (1,759)	[2]	$ (1,369)
Total realized/unrealized gains (losses) included in Net earnings	204		(589)		(211)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0		0		0
Purchases and issuances	(545)		(300)		(277)
Sales and settlements	163		106		98
Transfer into Level 3	0		0		0
Transfer out of Level 3	0		0		0
Financial liabilities, Ending Balance	(2,720)	[3]	(2,542)	[1]	(1,759)	[2]
Embedded derivatives
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, Beginning Balance	(2,542)		(1,759)		(1,369)
Total realized/unrealized gains (losses) included in Net earnings	204	[4]	(589)	[5]	(211)	[6]
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0		0		0
Purchases and issuances	(545)		(300)		(277)
Sales and settlements	163		106		98
Transfer into Level 3	0		0		0
Transfer out of Level 3	0		0		0
Financial liabilities, Ending Balance	$ (2,720)		$ (2,542)		$ (1,759)

[1] As previously discussed, these tables exclude the portion of MIE liabilities allocated to Level 3, which are derived from the fair value of the MIE assets.

[2] As previously discussed, these tables exclude the portion of MIE liabilities allocated to Level 3, which are derived from the fair value of the MIE assets.

[3] As previously discussed, these tables exclude the portion of MIE liabilities allocated to Level 3, which are derived from the fair value of the MIE assets.

[4] Total realized/unrealized gains (losses) included in net earnings for the embedded derivatives reflects losses related to the unlocking of actuarial assumptions of $44 million in 2018.

[5] Total realized/unrealized gains (losses) included in net earnings for the embedded derivatives reflects losses related to the unlocking of actuarial assumptions of $25 million in 2017.

[6] Total realized/unrealized gains (losses) included in net earnings for the embedded derivatives reflects losses related to the unlocking of actuarial assumptions of $17 million in 2016.